1. Field of Invention
This invention is directed to a method and apparatus for disposing of toxic waste materials, specifically halogenated hydrocarbons, by combustion in a modified piston type internal combustion engine.
2. Description of the Prior Art
The traditional method of using selected landfill sites to dispose of hazardous materials has come under serious review at both local and national levels since the environmental impact of recent episodes such as that which occurred at Love Canal. The instability of long term, safe, underground storage of toxic wastes has made this technique, which annually disposes of 250 million tons of waste, a questionable solution to the nation's toxic waste management problem. The hydrological interaction of waste materials stored in pits, lagoons, or deep wells with the underground water table; the bioconversion of stored materials; and the potential leakage of these materials are but a few of the major problems which will require expensive perpetual monitoring of such sites. For example, at 50 of the nation's 800 toxic waste wells, system failures have been experienced and reported, and nearly half of the 508 dump sites have also experienced irreversible failures, i.e., leakage of waste material into underground water supplies.
Incineration systems, biological treatment, and chemical neutralization are but a few of the technologies being actively pursued as alternatives to achieve an acceptable destruction and removal efficieny (DRE) of toxic waste materials while eliminating the problems associated with burial. Combustion of hazardous waste has been chiefly via incineration, rotary kilns, or coincineration. An example of an incineration system is disclosed in U.S. Pat. No. 4,462,318.
Liquid injection incinerators, designed for meeting DRE, have been built for specific pumpable liquids, but poor operational records, emission levels of PCB, fly ash, and health safety have clouded the potential success of this technology. Incineration at sea using liquid injection incinerators additionally faces environmental questions of potential spills and long-term ability of the ocean to absorb the emitted combustion effluent. Coincineration in existing systems, in addition to being less efficient, produces significant corrosion and a reduction in the reliability of the incineration system.
The Environmental Protection Agency has determined that the liquids found in a majority of abandoned dump sites consist chiefly of toluene, benzene, and chloroform. In addition, 25 compounds were found to account for more than two-thirds of the observed material, including 11 chlorinated hydrocarbons, 4 hydrocarbons and 7 heavy metal elements. Chlorinated hydrocarbons are a major part of most toxic wastes and are found in PCB's, pesticides, herbicides, and even Agent Orange. The ability to destructively degrade gaseous and liquid hydrocarbons by efficient, safe combustion would be a major contribution to the removal of these toxic wastes from the environment.
Methods have been proposed to burn toxic waste materials, including PCB's, in diesel engines. U.S. Pat. No. 4,108,113 describes a process in which waste vapors are mixed with air, introduced into the combustion chamber of a diesel engine, compressed and combusted at the end of the compression stroke by introducing a diesel fuel into the chamber. U.S. Pat. No. 4,154,811 and 4,400,396 disclose similar processes for liquid waste materials, particularly PCB's. Each of these various processes require that a substantial amount of diesel fuel be employed to effect combustion in the combustion chamber of the engine. In addition, in most cases, supplemental treatments of the exhaust gases from the combustion chamber are necessary to insure satisfactory removal of non-combusted toxic materials.
While the prior art methods have achieved some success in disposing of toxic substances, there remains a need in the art for a method of disposing of toxic substances, particularly halogenated hydrocarbons, which achieves substantially complete disposal of these substances in a more efficient manner than heretofore proposed.